Understanding Synaesthesia

Synaesthesia (from the Greek syn, “together,” and aisthesis, “sensation”) is a fascinating neurological trait in which stimulating one sense automatically triggers an experience in another. For someone with synaesthesia, the number 7 might always appear turquoise, the word “Tuesday” might taste like toast, or a burst of trumpet might paint a streak of orange across their mind’s eye. It isn’t a disorder, an illness, or a trick of the imagination — it’s simply a different, richly cross-wired way of perceiving the world, and researchers estimate it shapes the everyday experience of tens of millions of people.

How It Works: The Science Behind the Senses

Most brains keep sensory processing fairly separate: sound stays in the auditory cortex, colour stays in the visual cortex, and so on. In synaesthetic brains, these regions appear to be more densely cross-connected, so activity in one sensory area spills over and activates another. The leading theory points to extra neural connections that, in most people, get “pruned away” during early childhood but remain intact in synaesthetes. The trait also tends to run in families, and researchers have linked it to genes (including TBR1) involved in how the brain wires itself.

Three Broad Categories

• Congenital Synaesthesia  — present from early childhood, the most common and most studied form, believed to arise from innate differences in brain wiring.
• Acquired synaesthesia — emerges later in life, usually following a brain injury, stroke, or sensory loss.
• Drug-induced synaesthesia — a temporary cross-sensory experience triggered by hallucinogens, distinct from the lifelong developmental trait.

The Many Faces of Synaesthesia

Researchers have documented more than 80 distinct types. Some of the most common include:

• Grapheme–colour synaesthesia — letters and numbers each carry their own consistent colour.
• Chromesthesia (sound–colour) — sounds, music, or voices evoke colours, shapes, or movement.
• Lexical–gustatory synaesthesia — specific words or sounds trigger distinct tastes.
• Mirror-touch synaesthesia — watching someone else be touched produces a physical sensation on one’s own body.
• Spatial-sequence synaesthesia — numbers, months, or dates are mapped onto a precise location in space, like a mental calendar or number line.
• Ordinal-linguistic personification — letters, numbers, or days of the week each have their own personality.

How Common Is Synaesthesia

Estimates vary depending on how researchers test for it, but most studies put developmental synaesthesia at roughly 2–4% of the population — and for some specific types, such as time-space synaesthesia, it may be as high as 1 in 8 people. Grapheme–colour synaesthesia, the most-studied form, appears somewhat more common among women and in creative professions, though it occurs across all genders, ages, and cultures.

Synaesthesia and Creativity: Famous Synaesthetes

Because synaesthesia naturally blends sensory domains, it has long been associated with artistic and creative thinking. Composers Duke Ellington and Franz Liszt both described seeing colour in sound, physicist Richard Feynman saw equations in colour, novelist Vladimir Nabokov experienced letters as colours, and contemporary artists including Pharrell Williams and Billie Eilish, have spoken publicly about composing music through colour and shape. Many of these accounts are self-reported rather than clinically tested, but they offer a vivid window into how differently a synaesthetic mind can experience sound, language, and colour.

Myths vs. Facts

• Myth: Synaesthesia is a disorder that needs treatment. Fact: It isn’t a disease or a malfunction. Most synaesthetes describe it as a pleasant, integral part of how they experience the world, and no treatment is needed.
• Myth: It’s just a vivid imagination or a figure of speech. Fact: Synaesthetic sensations are automatic, involuntary, and remain highly consistent over a lifetime — a testable trait, not a creative flourish.
• Myth: Anyone can train themselves to “become” synaesthetic. Fact: While practice can strengthen sensory associations, genuine developmental synaesthesia appears to require a particular kind of brain wiring present from childhood.
• Myth: All synaesthetes experience it the same way. Fact: With more than 80 recorded types, even two people with the “same” type rarely share identical colour-letter or sound-taste pairings.

Curious Whether You’re a Synaesthete?

If any of this sounds familiar — numbers with personalities, days of the week in colour, music you can almost touch — you may be a synaesthete yourself. Take the short screening test below to explore your own sensory cross-connections, or scroll down to meet our synaesthesia curator, James Wannerton.